New 45-70 Question

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30carbnut posted this 31 January 2017

Hello all. I have been studying the 45-70 cartridge and firearm for long range for about 5 years. I have built my first rifle in .30 WCF from scratch (Check out my thread) that I took around 3 years of studying to gather information about how to do it, now I want to build a long range 45-70. The question is about rate of twist, number of grooves and barrel length. All of my research has led me to a 28"- 30” barrel with a 3 groove 1:18” twist. What would be your suggestion? I plan on this being a 45-70/80-500 Lead boolit load in a 2.4” case. Thanks in advance for any input.

NRA Life member since 1976

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Bud Hyett posted this 06 February 2017

There is a webpage discussing shooting the .45-70 at two miles. The rifles are a Trapdoor, Sharps Borchardt, and Martini-Henry in .577/450. In the articles, they discuss twist rates and effects. 

http://home.earthlink.net/~sharpsshtr/CritterPhotos/SandyHook/SandyHook.html

 

Farm boy from Illinois, living in the magical Pacific Northwest

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David Reiss posted this 31 January 2017

The 18” twist would be sufficient for 500 gr, bullets. I know some have even gone with a 16” twist, but you will find some that will argue that a 16” twist might over rotate bullets. My thought is that maybe somewhat of an myth. However I think you will be satisfied with the 18” twist. 

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
-Services: Wars Fought, Uprisings Quelled, Bars Emptied, Revolutions Started, Tigers Tamed, Assassinations Plotted, Women Seduced, Governments Run, Gun Appraisals, Lost Treasure Found.
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Ken Campbell Iowa posted this 02 February 2017

pac-nor barrels ... back when we were testing barrels pac-nor were excellent .   no experience lately .

ken

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SierraHunter posted this 02 February 2017

I've got a couple newer pacnor barrels in long range calibers (6.5/06 Ackley and a couple others) and they are most excellent.

There is a guy that does 3 groove rebores, and I have a couple of his barrels, and they all shoot cast most excellent. My 3 JES 3 groove 375 Whelen may be the most accurate big bore I own.

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30carbnut posted this 31 January 2017

Thank you for the info it will be very useful. The long range Springfield rifle that they were using in 1879 had a 33” barrel with 3 grooves and 1:18 twist and this is what I have based my observations on, thus why the questions, looking for all of the knowledge that I can get From real experience with the cartridge and rifle before I start the journey of building the rifle.

NRA Life member since 1976

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rmrix posted this 31 January 2017

By Longrange I assume you mean 800y - 1000y

A three groove barrel holds no advantage.  Springfield put them on their issue rifles and maybe they put 3-groove 18T barrels on the few target rifles they made because they could make them  too. I don't know.

 

Unless you can make your own three groove barrel you are most likely to find five and six groove 0.450 - 0.458” barrels, both 16 and 18T.  Either twist has its strong points.

Heaver bullets (longer) 1.425"and greater shot in switchy winds may do better with the faster twist. Shorter bullets and calm wind days do very well with 18T.

Those opinions are subjective. They are however based on more 150 LR matches and twice that many practice and load test days shot at 800-1000y. I am somewhat opinionated.

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30carbnut posted this 01 February 2017

Thank you for your very informative reply, Yes I am talking about 800 + yards.I have been looking around at barrels for a while now, what would you think about an 8 groove 1:18T barrel? I am not set on the 3 groove or the 18T I am just looking for information from people like you who have the experience shooting at these ranges. All of my research will ultimately save me a lot of heartache, because after building a rifle that takes the better part of a year to build and turns out that it won't shoot because of a bad choice of groove and twist rate would be very disheartening.  

NRA Life member since 1976

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David Reiss posted this 01 February 2017

Since you didn't say that you wanted to shoot long distance, I didn't take that into my recommendation. With that now disclosed I would go with the 1-16” twist so that longer / heavier bullets could be used and not worry about over-stabilization with lighter bullets, a theory which I don't subscribe to.  

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
-Services: Wars Fought, Uprisings Quelled, Bars Emptied, Revolutions Started, Tigers Tamed, Assassinations Plotted, Women Seduced, Governments Run, Gun Appraisals, Lost Treasure Found.
- Also deal in: Land, Banjos, Nails, Firearms, Manure, Fly Swatters, Used Cars, Whisky, Racing Forms, Rare Antiquities, Lead, Used Keyboard Keys, Good Dogs, Pith Helmets & Zulu Headdresses. .

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rmrix posted this 01 February 2017

I have been looking around at barrels for a while now, what would you think about an 8 groove 1:18T barrel?

 

All of my research will ultimately save me a lot of heartache, because after building a rifle that takes the better part of a year to build and turns out that it won't shoot because of a bad choice of groove and twist rate would be very disheartening. 

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rmrix posted this 01 February 2017

The 40 and 45 cal barrels are often made in 8 groove. Many of the available barrels LR competitors put on their rifles are 8 groove and though it is above my pay grade to comment on what is best, they are often about 2 to 1 grooves to land.

 

Worth noting, getting your rifle correct the first time, in other words doing you homework, is great!

If by chance your rifle does not shoot like you hope for, you can always re-barrel it. (the whole rifle is not lost)

Even the best barrel makers can turn out a dud now and then.

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Ken Campbell Iowa posted this 01 February 2017

re:  no. of grooves ::  in testing 22 rf barrels we tried 2, 3, 4, 5, 6  in premium barrels.   there was some thinking that the 2-grooves didn't shoot quite as well in the wind ... they shot better indoors than outdoors ... 

however we could not tell any difference in the other choices .  and i would expect in the larger diameter 45 cal. it would be even less sensitive to number of grooves ...

so that would suggest that would allow you to concentrate of the other parameters of your barrel .  and if you like 3 grooves, that should be just fine, but maybe ( krieger ) doesn't make 3 groove ... no problem .    BTW we found cm and ss barrels to be equally accurate ...   and finally, surprisingly ( ? ) ... my most accurate barrel was a douglas cm in match select and cryoed .......  as mentioned above, with barrels it helps to be lucky ...

for barrels that into which i thought i might recut different chambers ... i left 5 or 6 inches of straight diameter at the breech end ... then started the straight taper to the muzzle .  this also puts a little weight between your hands, not a bad thing in a 45-70 ( g ) ...

love your project, please keep us informed .  we need to learn along with you .

ken

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30carbnut posted this 01 February 2017

Thank you all, this is the information that I am looking for. Anyone have any comments about PAC-NOR and McGowen Barrel quality?

NRA Life member since 1976

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OU812 posted this 01 February 2017

I know my Browning 1885 BPCR has a Badger barrel (hand lapped) with about 6” of choke at muzzle. You can feel it when you push a patch down bore.

Buy lots of lead and clean barrel often (between every shot) windex works well.

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OU812 posted this 02 February 2017

BP Cartridge Reloading Manual by by Mike Venturino and Steven P Garbe is a good book.

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ClydeF posted this 22 October 2022

There is a lot of loading data out there on 45-70 loads.  1873 loads, 1886 & 1895 loads, and even Ruger no 1 & I believe 3 loads.  I have a number of 45-70s and a 45-90.  I am looking for smokeless powder loads with cast bullets for both of my Sharps.  An Italian conversation in 45-70 and a Shiloh 1874 long range express.  Both shoot BP well but want to try smokeless.

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